Semiconductor Module

This application is based upon and claims the benefit of priority to Japanese Patent Application No. 2024-159705, filed on Sep. 17, 2024, the entire contents of which are incorporated herein by reference.

The present invention relates to a semiconductor module that includes a wiring board on which a semiconductor element is mounted and a heat dissipation base bonded to the wiring board.

Typically, as a semiconductor module used for a power converter or the like, a semiconductor module or the like has been known in which a wiring board on which a semiconductor element is mounted is bonded to a heat dissipation base (for example refer to JP 2013-197432 A, JP 2022-024309 A, JP 2012-114203 A, JP 2005-039081 A, JP 2004-134746 A, and JP 7233604 B). In this type of semiconductor module, the wiring board includes an insulating layer such as a ceramic substrate provided with conductor layers on a front and a rear sides and is bonded to the heat dissipation base with a bonding material such a solder on a rear surface side of the wiring board.

When a bonding material for bonding a wiring board to a heat dissipation base is crushed during melting due to a weight of the wiring board, a mounted part, and a jig, a contact area with an insulating layer increases. Then, at the time when the bonding material is cooled (at the time of heat shrinking), the insulating layer having a relatively small linear expansion coefficient is pulled by the bonding material and a conductor layer having a relatively large linear expansion coefficient. Since the insulating layer is not bonded to the bonding material, a stress concentrates at a boundary between the bonding material and the conductor layer so that a crack may occur.

According to one aspect, an object of the present invention is to provide a semiconductor module that can suppress occurrence of a crack in an insulating layer of a wiring board.

A semiconductor module according to one mode includes a semiconductor element, a wiring board on which the semiconductor element is mounted, and a heat dissipation base bonded to the wiring board with a bonding material, in which the wiring board includes an insulating layer, a first conductor layer provided on a first surface of the insulating layer on a side of the semiconductor element, and a second conductor layer provided on a second surface of the insulating layer on a side of the heat dissipation base, in a cross section passing through a corner of the insulating layer in plan view and the corner of the second conductor layer, a distance from the second conductor layer to a peripheral edge of the bonding material on the second surface is equal to or less than a thickness of the bonding material between the second conductor layer and the heat dissipation base, a non-bonded portion is provided around the bonding material on the heat dissipation base, wettability between the bonding material and the second conductor layer and wettability between the bonding material and the heat dissipation base are larger than wettability between the non-bonded portion and the bonding material, and in the cross section, a distance from the second conductor layer to the non-bonded portion in plan view is equal to or less than a distance from the second conductor layer to a peripheral edge of the insulating layer on the second surface.

A semiconductor module according to another mode includes a semiconductor element, a wiring board on which the semiconductor element is mounted, and a heat dissipation base bonded to the wiring board with a bonding material, in which the wiring board includes an insulating layer, a first conductor layer provided on a first surface of the insulating layer on a side of the semiconductor element, and a second conductor layer provided on a second surface of the insulating layer on a side of the heat dissipation base, and in a cross section passing through a corner of the insulating layer in plan view and the corner of the second conductor layer, a distance from the second conductor layer to a peripheral edge of the insulating layer on the second surface is equal to or less than a thickness of the bonding material between the second conductor layer and the heat dissipation base.

According to the above mode, it is possible to suppress occurrence of a crack in an insulating layer of a wiring board.

1 1 Hereinafter, a semiconductor moduleaccording to an embodiment and other embodiments of the present invention will be described in detail with reference to the drawings. Note that each axis of X, Y, and Z in each figure to be referred is illustrated for the purpose of defining a direction or each plane in the illustrated semiconductor moduleor the like. The X, Y, and Z axes are orthogonal to each other and form a right-handed system. In the following description, a Z direction may be referred to as a vertical direction. Furthermore, a surface including the X axis and the Y axis may be referred to as an upper surface or a lower surface.

1 1 1 Such directions and planes are terms used for convenience of description. Thus, depending on an attachment posture of the semiconductor moduleor the like, a correspondence relationship with the X, Y, and Z directions may vary. For example, here, a surface facing a Z direction positive side (+Z direction) in a member forming the semiconductor moduleis referred to as an upper surface, and a surface facing a Z direction negative side (−Z direction) is referred to as a lower surface. However, the surface facing the Z direction negative side may be referred to as the upper surface, and the surface facing the Z direction positive side may be referred to as the lower surface. Furthermore, here, the plan view means a case where the upper surface (XY plane) of the semiconductor moduleor the like is viewed in a perspective manner from the Z direction positive side toward the Z direction negative side.

1 An aspect ratio and a magnitude relationship between respective members in each figure are merely schematically represented, and do not necessarily coincide with a relationship in the semiconductor moduleor the like actually manufactured. For convenience of description, there is a case where the magnitude relationship between the members might be exaggerated. In addition, the shapes of the same members may be different between different drawings.

1 In the following description, as an example of the semiconductor moduleaccording to the embodiment and the other embodiments, a device is exemplified that is applied to a power converter such as an industrial or an in-vehicle motor inverter device. Therefore, in the following description, detailed description of the same or similar configuration, function, operation, assembly method, and the like as or to those of a known semiconductor module will be omitted.

1 FIG. 2 FIG. 1 FIG. 1 is a plan view illustrating a semiconductor moduleaccording to an embodiment.is a cross-sectional view taken along a line II-II of.

1 10 20 30 1 40 50 1 FIG. 2 FIG. The semiconductor moduleillustrated inincludes a plurality of semiconductor elements, a plurality of wiring boards, and a heat dissipation base. Furthermore, the semiconductor moduleincludes a case(illustrated by dash-double-dot line that is imaginary line) and a sealing materialillustrated in.

10 20 1 20 10 20 1 FIG. The semiconductor elementis mounted on the wiring board. In the example in, the semiconductor moduleincludes the four wiring boardsaligned by two in each an X direction and a Y direction and the semiconductor elementsaligned by eight on each of the four wiring boards.

10 10 10 For example, the semiconductor elementis an insulated gate bipolar transistor (IGBT) that is a switching element, a free wheeling diode (FWD) element that is a diode element, or the like. As the semiconductor element, another semiconductor element such as a reverse conducting (RC)-IGBT element in which the switching element and the diode element connected in antiparallel to the switching element are integrated may be arranged. The switching element and the diode element in the semiconductor elementare not limited to be formed on a Si substrate, and may be formed on a semiconductor substrate using a wide band gap semiconductor such as Silicon Carbide (SiC) or Gallium Nitride (GaN), for example. Furthermore, the switching element may include, for example, a SiC metal oxide semiconductor field effect transistor (MOSFET), a bipolar junction transistor (BJT), or the like. Furthermore, the diode element may include, for example, a schottky barrier diode (SiC-SBD), a junction barrier schottky (JBS) diode, a merged PN schottky (MPS) diode, a PN diode, or the like.

10 10 21 1 10 21 2 1 40 20 A main electrode provided on an upper surface of the semiconductor elementis electrically connected to the another semiconductor element, a first conductor layer, or the like by a main current wiring line W. Furthermore, a control electrode (for example, gate electrode) provided on the upper surface of the semiconductor elementis electrically and indirectly or directly connected to a control terminal (not illustrated) via the first conductor layerby a control wiring line W. It is preferable that a main terminal that is an input terminal or an output terminal of the semiconductor moduleand the control terminal be, for example, integrally fixed to the case(illustrated by dash-double-dot line that is imaginary line) to be described later that covers around the four wiring boards.

20 30 22 20 21 22 23 20 20 Each of the four wiring boardsis bonded to the single common heat dissipation base, with a bonding material S such as solder, on a lower surface (second conductor layer). The wiring boardhas a rectangular shape in plan view and includes the first conductor layer, the second conductor layer, and an insulating layer. The wiring boardmay be, for example, a direct copper bonding (DCB) substrate or an active metal brazing (AMB) substrate. The wiring boardmay be referred to as a laminated substrate, an insulating circuit substrate, an insulating heat dissipation circuit substrate, or the like.

21 23 23 10 21 21 10 1 2 21 1 2 1 2 1 a The first conductor layeris, for example, a member that functions as a wiring member in an inverter circuit and is provided to be separated as a plurality of parts on a first surfaceof the insulating layeron a side of the semiconductor elementby a metal plate, a metal foil, or the like of copper, aluminum, or the like. The first conductor layeris electrically connected to the another first conductor layer, the main electrode, the main terminal, the control terminal, or the like provided on the upper surface of the semiconductor element, by the main current wiring line Wor the control wiring line W. The first conductor layermay be referred to as a conductor plate, a conductor pattern, a conductive layer, a wiring pattern, or the like. The main current wiring line Wand the control wiring line Ware, for example, metallic bonding wires. The main current wiring line Wand the control wiring line W(in particular, main current wiring line W) may be replaced with another wiring line such as a lead formed by processing a metal plate such as a copper plate.

22 30 23 23 30 22 20 30 22 b The second conductor layeris, for example, a member that functions as a heat conducting member that conducts heat generated in the inverter circuit to the heat dissipation baseand is provided on a second surfaceof the insulating layeron a side of the heat dissipation baseby a metal plate, a metal foil, or the like of copper, aluminum, or the like. The second conductor layer(wiring board) is bonded to the heat dissipation basewith the bonding material S such as solder. The second conductor layermay be referred to as a heat dissipation layer, a heat dissipation plate, a heat dissipation pattern, a conductor pattern, or the like.

23 23 23 23 20 30 22 23 23 2 3 3 4 2 3 2 The insulating layeris, for example, a ceramic substrate. Although the insulating layeris not limited to a specific substrate, the insulating layermay be, for example, a ceramic substrate formed of a ceramic material such as aluminum nitride (AlN), aluminum oxide (AlO), silicon nitride (SiN), or a composite material of aluminum oxide (AlO) and zirconium oxide (ZrO). The insulating layermay be, for example, a substrate obtained by molding an insulating resin such as an epoxy resin, a substrate obtained by impregnating a base material such as a glass fiber with an insulating resin, a substrate obtained by coating a surface of a flat plate-shaped metal core with an insulating resin, or the like. Here, the bonding material S that is used to bond the wiring boardto the heat dissipation basecovers the second conductor layerand has contact with the insulating layer. However, the bonding material S does not need to have contact with the insulating layer.

10 20 20 10 20 Note that a shape, the arranged number, an arrangement location, or the like of the semiconductor elementand the wiring boardcan be appropriately changed. It is desirable that the plurality of wiring boardsbe arranged. However, the numbers of semiconductor elementsand wiring boardsmay be any number of one or more.

30 30 31 30 40 31 The heat dissipation basehas a rectangular shape in plan view. In the heat dissipation base, fastening holesare provided at four corners in plan view. The heat dissipation baseis fastened to a cooler (not illustrated) together with the case, with a screw to be inserted into the fastening hole.

30 10 30 30 30 31 30 6 FIG. 2 FIG. The heat dissipation baseis a member that functions as a heat conducting member that conducts heat generated by the semiconductor elementto the cooler, and is formed of a metal plate such as a copper plate or an aluminum plate, for example. In order to radially push and spread a thermal conductive material such as thermal grease or a thermal compound to be inserted between the heat dissipation baseand the cooler from the center of the heat dissipation base, as illustrated in, the entire heat dissipation baseis warped, for example, by press working so that a lower surface of a metal plate having a flat plate shape becomes a convex curved surface and an upper surface becomes a concave curved surface. After being fastened to the cooler with the screw to be inserted into the fastening hole, the shape of the heat dissipation basebecomes closer to a flat plate shape as illustrated in.

40 10 20 41 40 30 30 For example, the casehas a quadrangular cylindrical shape of which a center axis is the Z direction and houses the semiconductor elementand the wiring boardin a hollow portion. For example, the caseis fixed to a peripheral edge of the upper surface of the heat dissipation baseby adhesion and is fastened to the cooler together with the heat dissipation base.

50 10 20 40 50 2 FIG. The sealing materialillustrated inseals the semiconductor elementand the wiring board, in the case. The sealing materialis, for example, an epoxy resin, silicone gel, or the like.

2 FIG. 30 30 21 22 30 23 As illustrated in, a solder resist R is provided around the bonding material S on the heat dissipation base. Since the solder resist R has a property for repelling the bonding material S even in contact with the bonding material S, the solder resist R is not bonded to the bonding material S. Note that the solder resist R is an example of a non-bonded portion. The non-bonded portion is not limited to the solder resist R, as long as the non-bonded portion is a processed portion where the bonding material S and the heat dissipation baseare not bonded. For example, the non-bonded portion may be a portion filled with a pencil or the like (coated portion with filling material such as graphite), an oxide film, or the like. Here, wettability between the solder resist R (non-bonded portion) and the bonding material S is lower than wettability between the bonding material S and the first conductor layer, the second conductor layer, and the heat dissipation base. Furthermore, the wettability between the solder resist R and the bonding material S is more preferably lower than wettability between the bonding material S and the insulating layer.

30 20 23 20 20 1 FIG. The solder resist R is arranged around the bonding material S on the heat dissipation base, for example, between the adjacent wiring boards(insulating layer), in plan view. In the example illustrated in, since the two wiring boardsare aligned in each of the X direction and the Y direction, the solder resist R has a cross shape in plan view. However, the solder resist R may be provided so as to surround the bonding material S, over an entire circumference of the wiring board.

20 23 23 23 23 23 21 23 21 23 1 3 FIGS.and 4 FIG. 4 FIG. 3 4 FIGS.and It is preferable that the solder resist R be provided with a width that the bonding material S does not pass over. Furthermore, in order to prevent connection of the bonding material S between the adjacent wiring boards, it is sufficient that the solder resist R be arranged in the cross shape described above across an entire region between the adjacent insulating layers, in plan view, as illustrated in. Furthermore, as illustrated in, the solder resist R may be arranged only at the corner of the insulating layer, in plan view. This corner may be only a portion where the corners of the two or four insulating layersface each other or may be only a portion where the corners of the four insulating layersface each other. Although the solder resist R illustrated inhas a right triangle having two sides parallel to a peripheral edge of the insulating layerin plan view, the solder resist R may have any shape. Note that, in, since the first conductor layerand the insulating layerare located above the bonding material S and the solder resist R, the first conductor layerand the insulating layerare illustrated as dash-double-dot lines that are imaginary lines.

2 FIG. 1 FIG. 2 FIG. 23 22 1 22 23 23 2 22 30 23 23 b Here, as illustrated in, in a II-II cross section in(cross section passing through corner of insulating layerin plan view and corner of second conductor layer), a distance (length L) from the second conductor layerto a peripheral edge of the bonding material S on the second surfaceof the insulating layeris equal to or less than a thickness (length L) of the bonding material S between the second conductor layerand the heat dissipation base. Note that the cross section inextends in a diagonal direction D of the insulating layerin plan view. Furthermore, although the peripheral edges of the bonding material S and the insulating layeron the cross section can be said as the corner, the peripheral edges may be curved.

2 FIG. 4 22 30 3 22 23 23 4 3 23 4 b Furthermore, in the cross section in, a distance (length L) from the second conductor layerto the solder resist R (same as distance to peripheral edge of bonding material S on heat dissipation base) in plan view (direction orthogonal to thickness direction (Z direction) of bonding material S (in XY plane)) is equal to or less than a distance (length L) from the second conductor layerto the peripheral edge of the insulating layeron the second surface. Note that, if the length Lis shorter than the length L, the solder resist R is located below the insulating layer. As an example, the length Lis equal to or less than 1 mm.

2 FIG. 4 22 30 5 21 23 23 a Furthermore, in the cross section in, the distance (length L) from the second conductor layerto the peripheral edge of the bonding material S on the heat dissipation base(same as distance to solder resist R) in plan view is shorter than a distance (length L) from the first conductor layerto the peripheral edge of the first surfaceof the insulating layer.

2 FIG. 4 22 30 6 23 30 Furthermore, in the cross section in, the distance (length L) from the second conductor layerto the peripheral edge of the bonding material S on the heat dissipation base(same as distance to solder resist R) in plan view is longer than a distance (length L) between the insulating layerand the heat dissipation basein the thickness direction (Z direction) of the bonding material S.

2 FIG. 2 FIG. 5 21 23 23 3 22 23 23 5 3 a b Furthermore, in the cross section in, although the distance (length L) from the first conductor layerto the peripheral edge of the first surfaceof the insulating layeris substantially the same as the distance (length L) from the second conductor layerto the peripheral edge of the insulating layerof the second surfacein, the distance (length L) is preferably longer than the length L.

23 2 23 23 30 30 12 11 23 23 13 12 14 13 23 30 5 FIG. Here, the peripheral edge (corner) of the insulating layeron the cross section in FIG.is preferably a portion adjacent to the another insulating layer. Furthermore, as illustrated in, the solder resist R preferably has a longitudinal direction wide portion Ra and a lateral direction wide portion Rb, in a portion where the corners of the two or four insulating layersare adjacent to each other. The longitudinal direction wide portion Ra extends in a longitudinal direction (Y direction) of the heat dissipation base, and the lateral direction wide portion Rb extends in a lateral direction (X direction) of the heat dissipation base. In the solder resist R, a width (length L) from an intermediate position P of the longitudinal direction wide portion Ra and the lateral direction wide portion Rb is longer than widths (length L) from an intermediate position P of the two insulating layersin a portion where sides of the two insulating layersare adjacent to each other. Furthermore, a length (L) of the longitudinal direction wide portion Ra extending in the longitudinal direction (Y direction) is longer than the widths (length L) from the intermediate position P of the longitudinal direction wide portion Ra and the lateral direction wide portion Rb. Furthermore, a length (L) of the lateral direction wide portion Rb extending in the lateral direction (X direction) is, for example, twice or more than the length (L) of the longitudinal direction wide portion Ra extending in the longitudinal direction (Y direction). Note that the longitudinal direction wide portion Ra and the lateral direction wide portion Rb may be provided only in a portion where the corners of the four insulating layersare adjacent to each other. Furthermore, only the lateral direction wide portion Rb, of the longitudinal direction wide portion Ra and the lateral direction wide portion Rb, may be provided. Furthermore, in a case where the heat dissipation basehas a square shape in plan view or the like, the lengths of the wide portions (longitudinal direction wide portion Ra and lateral direction wide portion Rb) may be the same.

30 30 20 20 10 23 23 30 23 20 6 FIG. 6 FIG. b Since the lower surface of the heat dissipation baseis a convex curved surface and the upper surface is warped to be a concave curved surface, as illustrated in, the bonding material S at the time of melting gathers at the center of the heat dissipation basein plan view due to the gravity (refer to arrow in). A fillet easily spreads in a portion where an amount of the bonding material S increases, and the wiring boardsinks due to weights of the wiring board(semiconductor element) and a jig so that the insulating layer(second surface) and the bonding material S easily come into contact with each other. On the other hand, since the amount of the bonding material S is small in the peripheral edge of the heat dissipation base, the fillet becomes smaller, and a contact area between the bonding material S and the insulating layerhardly increases even if the wiring boardsinks.

20 23 30 23 30 20 20 14 13 30 23 5 FIG. In this respect, as described above, the solder resist R is arranged between the adjacent wiring boards(insulating layer). Therefore, it is possible to suppress the spread of the bonding material S, in a portion on a center side of the heat dissipation basewhere the contact area with the insulating layeris likely to increase, than a portion on a peripheral edge side of the heat dissipation basewhere the wiring boardis not adjacent to the other wiring board. Furthermore, as illustrated in, the length (L) of the lateral direction wide portion Rb extending in the lateral direction (X direction) is longer than the length (L) of the longitudinal direction wide portion Ra extending in the longitudinal direction (Y direction). As a result, since the wide portion of the solder resist R (lateral direction wide portion Rb) is lengthened at the center in the longitudinal direction of the heat dissipation basewhere the contact area with the insulating layeris particularly likely to increase, it is possible to further suppress the spread of the bonding material S.

7 FIG. 21 22 23 23 22 22 30 b When the solder resist R is omitted (positions of solder resist R and bonding material S in a case where this solder resist R is provided are illustrated by dash-double-dot lines that are imaginary lines) as in a comparative example illustrated in, in the cross section, a distance (length L) from the second conductor layerto the peripheral edge of the bonding material S on the second surfaceof the insulating layeris longer than a thickness (length L) of the bonding material S between the second conductor layerand the heat dissipation base.

23 23 22 23 22 23 23 8 FIG. As a result, at the time of cooling the insulating layer, as illustrated in, the insulating layerhaving a relatively small linear expansion coefficient is pulled by the bonding material S and the second conductor layerhaving a relatively large linear expansion coefficient. Then, since the insulating layeris not bonded with the bonding material S, a stress concentrates at a boundary between the bonding material S and the second conductor layer, and a crack C occurs in the insulating layer. This crack C is likely to occur in a case where the insulating layerincludes a material with low flexural strength such as AlN-based ceramic.

2 FIG. 9 FIG. 7 FIG. 1 22 23 23 2 22 30 23 21 1 22 2 23 1 b On the other hand, by providing the solder resist R as in the present embodiment, in the cross section illustrated in, the distance (length L) from the second conductor layerto the peripheral edge of the bonding material S on the second surfaceof the insulating layeris equal to or less than the thickness (length L) of the bonding material S between the second conductor layerand the heat dissipation base, and the stress of the insulating layerduring a heat cycle is relaxed. Therefore, as illustrated in, in the present embodiment, as compared with a mode in which the length L(corresponding to length L) is longer than the length L(corresponding to length L) as in the comparative example illustrated in, a maximum main stress [MPa] of the insulating layeris reduced to about 0.55 times (652.9 →362.9). As a result, a ceramic crack occurrence rate caused by heating and cooling during an operation of the semiconductor moduleis reduced, for example, from 80% to 10 Parts Per Million (ppm) or less, and quality is improved.

1 10 20 10 30 20 20 23 21 23 23 10 22 23 23 30 23 22 1 22 23 23 2 22 30 30 22 30 23 4 22 3 22 23 23 a b b b. 2 FIG. In the embodiment described above, the semiconductor moduleincludes the semiconductor element, the wiring boardon which the semiconductor elementis mounted, and the heat dissipation basebonded to the wiring boardwith the bonding material S. The wiring boardincludes the insulating layer, the first conductor layerprovided on the first surfaceof the insulating layeron the semiconductor elementside, and the second conductor layerprovided on the second surfaceof the insulating layeron the heat dissipation baseside. In the cross section (refer to) passing through the corner of the insulating layerin plan view and the corner of the second conductor layer, the distance (length L) from the second conductor layerto the peripheral edge of the bonding material S on the second surfaceof the insulating layeris equal to or less than the thickness (length L) of the bonding material S between the second conductor layerand the heat dissipation base. Around the bonding material S on the heat dissipation base, the solder resist R (example of non-bonded portion) is provided. The wettability between the bonding material S and the second conductor layerand between the bonding material S and the heat dissipation baseis larger than the wettability between the solder resist R and the bonding material S. More preferably, the wettability between the solder resist R and the bonding material S is lower than the wettability between the insulating layerand the bonding material S. In the cross section, the distance (length L) from the second conductor layerto the solder resist R in plan view is equal to or less than the distance (length L) from the second conductor layerto the peripheral edge of the insulating layeron the second surface

23 1 22 23 23 2 22 30 23 23 22 22 23 23 20 2 FIG. b As a result, the solder resist R is located below the insulating layeror around the peripheral edge, so that, in the cross section in, the distance (length L) from the second conductor layerto the peripheral edge of the bonding material S on the second surfaceof the insulating layercan be equal to or less than the thickness (length L) of the bonding material S between the second conductor layerand the heat dissipation base. Therefore, at the time when the bonding material S is cooled (at the time of heat shrinking), at the corner of the insulating layerwhere the stress easily concentrates, even if the insulating layerhaving the relatively small linear expansion coefficient is pulled by the bonding material S and the second conductor layerhaving the relatively large linear expansion coefficient, the stress concentrating at the boundary between the bonding material S and the second conductor layerin the insulating layercan be relaxed. Therefore, according to the present embodiment, it is possible to suppress the occurrence of the crack C in the insulating layerof the wiring board.

1 20 23 23 Furthermore, in the present embodiment, the semiconductor moduleincludes the plurality of wiring boards, and the corner of the insulating layeron the cross section is adjacent to the another insulating layer.

23 22 23 23 20 As a result, in a portion where the plurality of insulating layersis adjacent to each other and where the stress is easily concentrated, the stress concentrating at the boundary between the bonding material S and the second conductor layerin the insulating layercan be relaxed. Therefore, it is possible to further suppress the occurrence of the crack C in the insulating layerof the wiring board.

4 22 30 5 21 23 23 a Furthermore, in the present embodiment, in the cross section, the distance (length L) from the second conductor layerto the peripheral edge (solder resist R) of the bonding material S on the heat dissipation basein plan view is shorter than the distance (length L) from the first conductor layerto the peripheral edge of the first surfaceof the insulating layer.

23 23 23 b As a result, even if the spread of the bonding material S increases and the contact area between the bonding material S and the second surfaceof the insulating layerincreases, an insulating distance along a surface of the insulating layercan be secured.

4 22 30 6 23 30 Furthermore, in the present embodiment, in the cross section, the distance (length L) from the second conductor layerto the peripheral edge (solder resist R) of the bonding material S on the heat dissipation basein plan view is longer than the distance (length L) between the insulating layerand the heat dissipation basein the thickness direction of the bonding material S.

As a result, it is possible to avoid a defect such that a crack or the like occurs in the bonding material S itself by a heat cycle due to narrowing of a width of the bonding material S.

5 21 23 23 3 22 23 23 a b Furthermore, in the present embodiment, in the cross section, the distance (length L) from the first conductor layerto the peripheral edge of the first surfaceof the insulating layeris longer than the distance (length L) from the second conductor layerto the peripheral edge of the second surfaceof the insulating layer.

23 23 23 b As a result, even if the spread of the bonding material S increases and the contact area between the bonding material S and the second surfaceof the insulating layerincreases, the insulating distance along the surface of the insulating layercan be secured.

22 23 Furthermore, in the present embodiment, the bonding material S covers the second conductor layerand is in contact with the insulating layer.

23 23 23 22 10 30 20 22 b Here, in the present embodiment, as described above, even if the bonding material S comes into contact with the second surfaceof the insulating layer, it is possible to suppress the occurrence of the crack C in the insulating layer. Therefore, by covering the second conductor layerwith the bonding material S, heat dissipation from the semiconductor elementto the heat dissipation basevia the wiring board(second conductor layer) can be enhanced.

10 FIG. 230 is a plan view illustrating the solder resist R on a heat dissipation base, according to a first modification of the embodiment.

2 10 20 40 50 1 10 FIG. 1 2 FIGS.and 10 FIG. A semiconductor moduleillustrated inincludes the semiconductor element, the wiring board, the case, the sealing material, and the like, similarly to the semiconductor moduleillustrated in. However, those are not illustrated in.

10 FIG. 10 FIG. 5 FIG. 223 230 30 230 231 As illustrated in, in the first modification, only two wiring boards (insulating layerillustrated as dash-double-dot line that is imaginary line) aligned in the Y direction are arranged. Therefore, the heat dissipation baseillustrated inhas a rectangular shape in plan view that is longer and thinner in the Y direction than the heat dissipation baseillustrated in. In the heat dissipation base, fastening holesare provided at four corners in plan view.

223 223 230 230 12 11 223 223 13 12 14 13 The solder resist R is arranged over an entire space between the adjacent insulating layers. Furthermore, the solder resist R includes the longitudinal direction wide portion Ra and the lateral direction wide portion Rb, in a portion where corners of the two insulating layersare adjacent to each other. The longitudinal direction wide portion Ra extends in a longitudinal direction (Y direction) of the heat dissipation base, and the lateral direction wide portion Rb extends in a lateral direction (X direction) of the heat dissipation base. In the solder resist R, a width (length L) of the longitudinal direction wide portion Ra and the lateral direction wide portion Rb is longer than a width (length L) from intermediate positions P of the two insulating layersin a portion where sides of the two insulating layersare adjacent to each other. Furthermore, a length (L) of the longitudinal direction wide portion Ra extending in the longitudinal direction (Y direction) is longer than the widths (length L) from the intermediate position P of the longitudinal direction wide portion Ra and the lateral direction wide portion Rb. Furthermore, a length (L) of the lateral direction wide portion Rb extending in the lateral direction (X direction) is longer than the length (L) of the longitudinal direction wide portion Ra extending in the longitudinal direction (Y direction).

11 FIG. 330 is a plan view illustrating the solder resist R on a heat dissipation base, according to a second modification of the embodiment.

3 10 20 40 50 1 11 11 FIG. 1 2 FIGS.and A semiconductor moduleillustrated inincludes the semiconductor element, the wiring board, the case, the sealing material, and the like, similarly to the semiconductor moduleillustrated in. However, those are not illustrated in FIG..

11 FIG. 11 FIG. 10 FIG. 323 230 230 330 331 As illustrated in, in the second modification, only six wiring boards (insulating layer) aligned in the Y direction are arranged. Therefore, the heat dissipation baseillustrated inhas a rectangular shape in plan view that is further longer and thinner in the Y direction than the heat dissipation baseillustrated in. In the heat dissipation base, seven fastening holesare provided to be aligned in the Y direction, at an end on one side and an end on another side in the X direction.

323 323 330 330 12 11 323 323 13 12 14 13 The solder resist R is arranged over an entire space between the adjacent insulating layers. Furthermore, the solder resist R includes the longitudinal direction wide portion Ra and the lateral direction wide portion Rb, in a portion where corners of the insulating layersare adjacent to each other. The longitudinal direction wide portion Ra extends in a longitudinal direction (Y direction) of the heat dissipation base, and the lateral direction wide portion Rb extends in a lateral direction (X direction) of the heat dissipation base. In the solder resist R, the width (length L) of the longitudinal direction wide portion Ra and the lateral direction wide portion Rb is longer than the width (length L) from intermediate positions P of the two insulating layersin a portion where sides of the two insulating layersare adjacent to each other. Furthermore, the length (L) of the longitudinal direction wide portion Ra extending in the longitudinal direction (Y direction) is longer than the widths (length L) from the intermediate position P of the longitudinal direction wide portion Ra and the lateral direction wide portion Rb. Furthermore, a length (L) of the lateral direction wide portion Rb extending in the lateral direction (X direction) is longer than the length (L) of the longitudinal direction wide portion Ra extending in the longitudinal direction (Y direction).

330 323 330 323 323 330 323 323 323 323 330 Note that, as described above, the bonding material S at the time of melting gathers at the center of the heat dissipation basein plan view due to the gravity, and the insulating layereasily comes into contact with the bonding material S. Therefore, the solder resist R may be provided only at the center of the heat dissipation basein the longitudinal direction (for example, between third insulating layerand fourth insulating layerfrom Y direction positive side) or only at the center and near the center of the heat dissipation basein the longitudinal direction (for example, between second insulating layerand third insulating layerfrom Y direction positive side and between fourth insulating layerand fifth insulating layerfrom Y direction positive side). Furthermore, the solder resist R may be wider than other portions at the center or near the center of the heat dissipation basein the longitudinal direction.

12 FIG. 1 FIG. 120 is a cross-sectional view (corresponding to line II-II in) illustrating a wiring boardor the like according to the other embodiments.

1 120 The present embodiment can be similar to the semiconductor moduleaccording to the embodiment described above, except that the solder resist R is omitted and some of dimensions of parts of the wiring boardare different. Therefore, description of overlapping matters is omitted.

120 20 121 122 123 120 12 FIG. 1 FIG. 10 FIG. 11 FIG. The wiring boardillustrated inhas a rectangular shape in plan view, similarly to the wiring boarddescribed above and includes a first conductor layer, a second conductor layer, and an insulating layer. Note that the number of wiring boardsmay be four as illustrated in, may be two as in the first modification illustrated in, or may be six as in the second modification illustrated inand is not particularly limited.

12 FIG. 123 122 3 122 123 2 122 30 1 122 123 123 2 122 30 b In the present embodiment, in a cross section (cross section in) passing through a corner of the insulating layerin plan view and the corner of the second conductor layer, a distance (length L) from the second conductor layerto a peripheral edge of the insulating layer(for example, corner in diagonal direction D) is equal to or less than a thickness (length L) of a bonding material S between the second conductor layerand a heat dissipation base. Therefore, as in the embodiment described above, in the cross section, the distance (length L) from the second conductor layerto the peripheral edge of the bonding material S on a second surfaceof the insulating layeris also equal to or less than the thickness (length L) of the bonding material S between the second conductor layerand the heat dissipation base.

3 123 123 122 122 123 122 10 To shorten the length Lin this way, it is preferable to reduce the size of the insulating layerso that the peripheral edge of the insulating layerapproaches the second conductor layeror to enlarge the second conductor layerso as to approach the peripheral edge of the insulating layer. By enlarging the second conductor layer, heat dissipation of the semiconductor elementcan be enhanced.

3 122 123 123 Other relationships in the length are similar to those in the embodiment described above. However, in particular, the distance (length L) from the second conductor layerto the peripheral edge (for example, corner) of the insulating layerbecomes shorter so that it becomes difficult to secure an insulating distance, for example, because the bonding material S spreads over an outer peripheral surface of the insulating layer.

12 FIG. 4 122 30 5 121 123 123 5 121 123 123 3 122 123 123 a a b From this viewpoint, in the cross section in, it is particularly effective that a distance (length L) from the second conductor layerto the peripheral edge of the bonding material S on the heat dissipation basein plan view is shorter than a distance (length L) from the first conductor layerto the peripheral edge of the first surfaceof the insulating layerand the distance (L) from the first conductor layerto the peripheral edge of the first surfaceof the insulating layeris longer than the distance (length L) from the second conductor layerto the peripheral edge of the second surfaceof the insulating layer.

12 FIG. 123 122 3 122 123 2 122 30 In the other embodiments described above, in the cross section in(cross section passing through corner of insulating layerin plan view and corner of second conductor layer), the distance (length L) from the second conductor layerto the peripheral edge of the insulating layer(for example, corner in diagonal direction D) is equal to or less than the thickness (length L) of the bonding material S between the second conductor layerand the heat dissipation base.

12 FIG. 1 122 123 123 2 122 30 123 122 122 123 123 120 b Therefore, as in the embodiment described above, in the cross section in, the distance (length L) from the second conductor layerto the peripheral edge of the bonding material S on the second surfaceof the insulating layercan be equal to or less than the thickness (length L) of the bonding material S between the second conductor layerand the heat dissipation base. Therefore, at the time when the bonding material S is cooled, even if the insulating layerhaving a relatively small linear expansion coefficient is pulled by the bonding material S and the second conductor layerhaving a relatively large linear expansion coefficient, a stress concentrating at a boundary between the bonding material S and the second conductor layerin the insulating layercan be relaxed. Therefore, according to the present embodiment, it is possible to suppress occurrence of a crack C in the insulating layerof the wiring board.

The semiconductor module according to the present invention is not limited to the embodiment described above, and various changes, substitutions, and modifications may be made without departing from the spirit of the technical concept. Furthermore, if the technical idea can be achieved in another manner due to the progress of the technology or by another derived technology, the technical idea may be carried out by using the manner. Therefore, the claims cover all embodiments that may be included within the scope of the technical idea.

12 FIG. 3 122 123 2 122 30 30 230 330 20 120 30 230 330 For example, as in the other embodiments, in the cross section in, the distance (length L) from the second conductor layerto the peripheral edge (for example, corner) of the insulating layermay be equal to or less than the thickness (length L) of the bonding material S between the second conductor layerand the heat dissipation base, and the solder resist R may be provided as in the embodiment. Furthermore, in the heat dissipation bases,, and, a base plate having a flat plate shape is warped by press working or the like, and the lower surface is warped to be a convex curved surface, and the upper surface bonded to the wiring boardsandis warped to be a concave curved surface. However, the shape of the heat dissipation bases,, andin the present invention is not limited to such a shape.

Hereinafter, some inventions described in the specification and drawings of the present application will be additionally described.

a semiconductor element; a wiring board on which the semiconductor element is mounted; and a heat dissipation base bonded to the wiring board with a bonding material, in which the wiring board includes an insulating layer, a first conductor layer provided on a first surface of the insulating layer on a side of the semiconductor element, and a second conductor layer provided on a second surface of the insulating layer on a side of the heat dissipation base, in a cross section passing through a corner of the insulating layer in plan view and the corner of the second conductor layer, a distance from the second conductor layer to a peripheral edge of the bonding material on the second surface is equal to or less than a thickness of the bonding material between the second conductor layer and the heat dissipation base, a non-bonded portion is provided around the bonding material on the heat dissipation base, wettability between the bonding material and the second conductor layer and wettability between the bonding material and the heat dissipation base are larger than wettability between the non-bonded portion and the bonding material, and in the cross section, a distance from the second conductor layer to the non-bonded portion in plan view is equal to or less than a distance from the second conductor layer to a peripheral edge of the insulating layer on the second surface. A semiconductor module including:

a semiconductor element; a wiring board on which the semiconductor element is mounted; and a heat dissipation base bonded to the wiring board with a bonding material, in which the wiring board includes an insulating layer, a first conductor layer provided on a first surface of the insulating layer on a side of the semiconductor element, and a second conductor layer provided on a second surface of the insulating layer on a side of the heat dissipation base, and in a cross section passing through a corner of the insulating layer in plan view and the corner of the second conductor layer, a distance from the second conductor layer to a peripheral edge of the insulating layer on the second surface is equal to or less than a thickness of the bonding material between the second conductor layer and the heat dissipation base. A semiconductor module including:

a plurality of the wiring boards, in which the corner of the insulating layer is adjacent to the another insulating layer. The semiconductor module according to supplementary note 1 or 2, further including:

in the cross section, a distance from the second conductor layer to the peripheral edge of the bonding material on the heat dissipation base in plan view is shorter than a distance from the first conductor layer to the peripheral edge of the insulating layer on the first surface. The semiconductor module according to any one of supplementary notes 1 to 3, in which

in the cross section, the distance from the second conductor layer to the peripheral edge of the bonding material on the heat dissipation base in plan view is longer than a distance between the insulating layer and the heat dissipation base in a thickness direction of the bonding material. The semiconductor module according to any one of supplementary notes 1 to 4, in which

in the cross section, the distance from the first conductor layer to the peripheral edge of the insulating layer on the first surface is longer than the distance from the second conductor layer to the peripheral edge of the insulating layer on the second surface. cl Supplementary Note 7 The semiconductor module according to any one of supplementary notes 1 to 5, in which

the bonding material covers the second conductor layer and has contact with the insulating layer. The semiconductor module according to any one of supplementary notes 1 to 6, in which

wettability between the non-bonded portion and the bonding material is lower than wettability between the insulating layer and the bonding material. The semiconductor module according to supplementary note 1, in which

As described above, the present invention has an effect of suppressing occurrence of a crack in an insulating layer of a wiring board, and is particularly useful for an industrial or electrical inverter device.